The present invention relates generally to cyclonic separators. In one particular application, the invention relates to a vacuum cleaner which uses the cyclonic separation of dirt from an air flow as the primary dirt separation mechanism.
The use of a cyclone, or multiple cyclones connected in parallel or series, has long been known to be advantageous in the separation of particulate matter from a fluid stream. Typically, a relatively high speed fluid stream is introduced tangentially to a generally cylindrical or frusto-conical container, wherein the dirty air stream is accelerated around the inner periphery of the container. The centrifugal acceleration caused by the travel of the fluid in a cyclonic stream through the cyclone causes the particulate matter to be disentrained from the fluid flow and, eg., to collect at the bottom of the container. A fluid outlet is provided for the extraction of the fluid from the centre of the top of the cyclone container, as is well known in the art.
A typical flow path in a cyclone separator is as follows. Fluid to be treated is introduced tangentially at a fluid inlet located at the upper end of the cyclone container (if the cyclone container is vertically disposed). The fluid stream rotates around the inner surface of the cyclone container, and spirals generally downwardly around the inner surface. At the bottom end of the cyclone container the fluid stream travels radially inwardly, generally along the bottom of the container and then turns upwardly and proceeds vertically up and out of the cyclone container. The particulate matter separating action of the cyclonic flow occurs substantially around the inner surface. Once the air moves inwardly to the centre of the container, and upwardly there through, there is little or no dirt separation achieved.
Various types of vacuum cleaners are traditionally produced. These include built in vacuum cleaners, canister vacuum cleaners and upright vacuum cleaners. Upright vacuum cleaners have a ground engaging portion (a cleaning head) and an upwardly extending or main body portion. The ground engaging portion typically has wheels for movement of the cleaning head across a floor and a suction inlet for the intake of dirty air into the vacuum cleaner. The upwardly extending portion comprises the filter means for removing dirt which is entrained in the air. The upwardly extending portion generally has a handle for guiding the vacuum cleaner across the floor.
Traditionally in upright vacuum cleaners, the motor to draw the dirty air through the vacuum cleaner is positioned in the ground engaging head and the upward extending portion is pivotally mounted to the upper portion of the ground engaging member at a position adjacent the motor.
The advantages of cyclonic separation have been combined with an upright vacuum cleaner to provide a household cyclonic vacuum cleaner, as shown in U.S. Pat. No. 4,593,429 to Dyson. As shown in FIG. 1, this vacuum cleaner 10 essentially comprises a large, outer cylindrical cyclone 12, with an inner cyclone 14 nested therein, which is mounted on a floor-cleaning head and provided with a push handle for convenient movement of the unit. A motor, located in the floor cleaning head, draws air through the cleaning head and into an intake conduit 16, which delivers air to the dirty air inlet 18 of the outer cyclone container 12. From the outer cyclone the air flows into inner, nested dust separating cyclone 14, and from there, continues on through the vacuum motor, which is positioned in the ground engaging member, to a clean air exhaust port.
The air intake conduit 16 connects the floor cleaning head and the dirty air inlet in air flow communication. Air intake conduit 16 extends upwardly along the outside of outer cyclone container 12 generally parallel to the longitudinal axis of the cyclones 12, 14. At a position adjacent air inlet 18 to outer cyclone 12, air intake conduit 16 bends 90xc2x0 twice to travel inwardly and to provide a tangential air flow to air inlet 18 of outer cyclone container 12.
In use, air intake conduit 16 may become blocked. If the blockage occurs at a midpoint of the conduit, it may be difficult to clear the blockage. While a clean out port may be provided, the port may not be located near where the blockage occurs. Further, the addition of a port increases the cost and complexity of the manufacture of the product.
A bend in a conduit for a fluid causes a turbulent pressure loss in the conduit as the fluid travels through the bend in the conduit and the greater the sharpness of the bend, the greater the pressure loss. The pressure loss in the air flow decreases the amount of suction which can be generated at the cleaning head of the vacuum cleaner for any given motor in the vacuum cleaner and therefore the efficiency of the vacuum cleaner.
In accordance with the instant invention, there is provided a vacuum cleaner having a source of dirty air to be treated and a housing, the cyclonic separator comprising a cyclone removably mounted in the housing and having a bottom, a fluid inlet, a wall having an inner surface and a longitudinally extending axis; and a fluid supply conduit extending along the length of the cyclone from the bottom to the fluid inlet, the fluid supply conduit conveying the dirty air substantially axially to the fluid inlet, the fluid supply conduit communicating with the source of dirty air when the cyclonic separator is in use, the fluid inlet redirecting the dirty air from an axial flow to a tangential flow and the fluid inlet is positioned within the cyclone.
In one embodiment, the fluid supply conduit extends through a central portion of the cyclone. The fluid supply conduit preferably extends coaxially with the axis of the cyclone and the fluid inlet preferably extends outwardly to the inner surface.
In another embodiment, the fluid inlet includes a curved portion without any 90xc2x0 elbows.
In another embodiment, the fluid inlet comprises at least a portion that extends in a continuous curve.
In another embodiment, the fluid inlet is curved in a first direction towards the inner surface of the wall and is curved in a second direction to introduce the dirty air tangentially to the cyclone. The fluid inlet may be curved so as to sequentially redirect the air in the first direction and then the second direction. Preferably, the fluid inlet is curved so as to simultaneously redirect the air in the first direction and the second direction.
In another embodiment, the fluid inlet has a curved portion to impart a rate of change of direction in the fluid travelling there through in two axis simultaneously.
In another embodiment, the fluid supply conduit extends longitudinally through the cyclone and the cyclone is removably mounted in the housing.
In another embodiment, the downstream end of the fluid inlet extends substantially horizontally.
In another embodiment, the downstream end of the fluid inlet extends towards the bottom of the cyclone.
In another embodiment, the downstream end of the fluid inlet extends towards the bottom of the cyclone at an angle of up to 10xc2x0 from a plane perpendicular to the axis.
In another embodiment, the cyclone has an outlet having a wall and a portion of the fluid inlet is nested within the outlet and a portion of the fluid inlet is positioned exterior the outlet.
In accordance with the instant invention, there is also provided a cyclonic separator having a source of fluid to be treated, the cyclonic separator comprising a cyclone having a bottom, a fluid inlet, a wall having an inner surface and a longitudinally extending axis, the fluid inlet having an upstream end and a downstream end; and, a fluid supply conduit extending substantially along the axis of the cyclone from the bottom to the upstream end of the fluid inlet, the fluid supply conduit communicating with the source of fluid when the cyclonic separator is in use, the fluid inlet is curved in a first direction towards the wall and is curved in a second direction to introduce the fluid tangentially to the cyclone.
In one embodiment, the cyclone has an outlet having a wall and at least a portion of the fluid inlet is nested within the outlet and extends through the wall of the outlet.
In another embodiment, the inlet comprises a duct extending from point S1 to point S2 and comprises a space curve around which the conduit is formed wherein the gradient of the space curve has at least two non-zero components which vary along the arc length of the curve. Preferably, the space curve comprises a helical segment.
Preferably, the helical segment is defined by S(t)=(G)*(cos(t),sin(t),t)xc2x7(x,y,z) whereby
(a) the gradient of the space curve has at least two non-zero components which vary along the arc length of the curve
(b) t1 less than t less than t2
(c) S(t2) is equal to S1; and,
(d) S(t2) is equal to S2.
Preferably, the duct comprises an envelope formed by a radius r out from the central space curve which is itself formed about a construction cylinder having a radius R and an axis wherein the conduit the duct has a radius r where r less than R and the space curve at S1 smoothly becomes a straight line coincident with the axis of the construction cylinder.
Preferably, the space curve at S2 smoothly becomes a straight line coincident with the derivative of S(t) at point S2 with respect to the parameter t.
In accordance with the instant invention, there is also provided a cyclonic separator having a source of fluid to be treated, the cyclonic separator comprising cyclone separation means having a longitudinally extending axis and a length; fluid supply conduit means extending substantially along the length of the cyclone separation means, the fluid supply conduit means communicating with the source of fluid when the cyclonic separator is in use; and, fluid inlet means for redirecting the fluid from a substantially axial flow for introduction tangentially to the cyclone means without any 90xc2x0 elbows.
In another embodiment, the cyclonic separator further comprises housing means for removably receiving the cyclonic separation means wherein the cyclone separation means has outlet means having a wall and a portion which is removable with the cyclone separation means from the housing means and the fluid inlet means passes through the wall of the outlet means.
In accordance with the instant invention, there is also provided a method comprising providing a fluid having a first element and a second element; conveying the fluid in a conduit longitudinally through a cyclone having a longitudinal axis and a longitudinally extending surface; conveying the fluid in a conduit laterally to the longitudinally extending surface; and, introducing the fluid into the cyclone and passing the fluid through the cyclone to remove at least a portion of the first element from the fluid and obtain at least one treated stream having a reduced concentration of the first element.
In one embodiment, the method further comprises conveying the fluid centrally through the cyclone.
In another embodiment, the method further comprises conveying the fluid around at least a portion of the longitudinal axis of the cyclone as the fluid passes outwardly from the central portion.
In another embodiment, the method further comprises providing centrifugal acceleration to the fluid as it passes outwardly from the central portion.
In accordance with the instant invention, there is also provided a fluid supply conduit comprising a curved portion to impart a rate of change of direction in the fluid travelling there through in two axis simultaneously.
In accordance with the instant invention, there is also provided a method comprising providing a fluid having a first element and a second element; conveying the fluid to a cyclone; introducing the fluid through an inlet to the cyclone to impart a rate of change of direction in the fluid travelling there through in two axis simultaneously; and passing the fluid through the cyclone to remove at least a portion of the first element from the fluid and obtain at least one treated stream having a reduced concentration of the first element.